Backpacks and other load carrier devices and systems are often designed to fit over the shoulders of a user who is carrying the load. Thus, the shoulder straps generally place the weight of the load on the user's shoulders. Additional straps generally serve to prevent the load from shifting laterally or from falling off the shoulders.
Backpacks are used by a wide range of users, both professional and non-professional. For example, non-professional users may include students, hikers, travelers, or parents of small children. Professional users may include firefighters, military or law enforcement personnel, forest or park rangers, tour guides, or rescue workers. A loaded backpack may be very heavy. For example, an infantry soldier, depending on the nature of a particular task or mission, may be required to carry weapons, ammunition, water, food, body armor, tools, communication equipment, and reconnaissance equipment. The weight of this equipment may, in some cases, be similar to the weight of the body of the person carrying the load.
When traveling large distances on foot, a loaded backpack may become extremely uncomfortable to carry. Excessive force may be exerted on the shoulders or back of the person carrying the backpack. In addition to causing discomfort, the excessive force could lead to back pain or injury.